The invention relates generally to the application of fluid materials and, in particular, to devices for use in jetting fluid materials.
Jetting devices may require different types of dispensing valves, or dispensing valve components, that are dedicated to different types of dispensing applications in electronic industry applications in which minute amounts of a fluid material are applied onto a substrate. A “jetting device” is a device which ejects, or “jets”, a droplet of material from a dispenser nozzle to land on a substrate, and wherein the droplet disengages from the dispenser nozzle before making contact with the substrate. Thus, in a jetting type dispenser, the droplet dispensed is “in-flight” between the dispenser and the substrate, and not in contact with either the dispenser or the substrate, for at least a part of the distance between the dispenser and the substrate. Numerous applications exist for jetting devices that dispense underfill materials, encapsulation materials, surface mount adhesives, solder pastes, conductive adhesives, and solder mask materials, fluxes, and thermal compounds. As the type of application for the jetting device changes, the type of jetting device must also adapt to match the application change.
One type of jetting device includes a valve device having a valve element configured to selectively engage a valve seat. During a jetting operation, the valve element of the jetting device is moved relative to the valve seat by a driving mechanism. Contact between the valve element and the valve seat seals off a discharge passage from a fluid chamber supplied with fluid material under pressure. Thus, to dispense droplets of the fluid material, the valve element is retracted from contact with the valve seat to allow a finite amount of the fluid material to flow through the newly formed gap and into the discharge passage. The valve element is then moved rapidly toward the valve seat to close the gap, which generates pressure that accelerates the finite amount of fluid material through the discharge passage and causes a droplet of the material to be ejected, or jetted, from an outlet of the discharge passage.
Jetting devices are configured for controlled movements above the substrate and the fluid material is jetted to land on an intended application area of a substrate. By rapidly jetting the material “on the fly” (i.e., while the jetting device is in motion), the dispensed droplets may be joined to form a continuous line. Jetting devices may therefore be easily programmed to dispense a desired pattern of fluid material. This versatility has made jetting devices suitable for a wide variety of applications in the electronics industry. For example, underfill material can be applied using a jetting device to dispense fluid material proximate to one or more edges of a chip, with the material then flowing under the chip by capillary action.
In conventional jetting devices, the valve element and the valve seat may tend to wear over time and with usage. As a consequence of this wear, the shape of the valve element and the valve seat are changed, and these shape changes can influence the characteristics of the fluid material being dispensed. For example, the size, shape, and weight of the fluid material dispensed during a jetting operation can vary as the shape of the valve element and the valve seat change. Changes in the size, shape, or weight of the dispensed fluid material are generally disfavored, as such changes disrupt the consistency of products treated with the jetting devices.
Moreover, conventional jetting devices are difficult to clean and maintain because their components are not constructed in a manner that allows simply disassembly and maintenance.